The trigeminal nerve is exposed by performing a craniotomy (small hole in the skull behind the ear ).
The most frequently involved cranial nerve dermatome is the ophthalmic division of the trigeminal nerve.
Within the brain stem, the signals traveling through the trigeminal nerve reach specialized clusters of neurones called the trigeminal nerve nucleus.
From there, the trigeminal nerve root continues back toward the side of the brain stem, and inserts into the pons.